Merc 240 starts on trailer not in the water

[Seadoocouple]

I have a 2002 challenger 2000 I picked it up with a hole in the haul so it's fixed and it starts right up but we took it to the water today and it wouldn't start so I pulled it out and it started so I left it run and backed it back into the water and it spit and died. It cranks over fine in the water and tries to start but does not, also the fuel tank is clear full and I don't know how old the fuel is also compression is 130 all the way around

 

[Tim75]

I have a 2002 challenger 2000 I picked it up with a hole in the haul so it's fixed and it starts right up but we took it to the water today and it wouldn't start so I pulled it out and it started so I left it run and backed it back into the water and it spit and died. It cranks over fine in the water and tries to start but does not, also the fuel tank is clear full and I don't know how old the fuel is also compression is 130 all the way around

What is the rpm on the trailer? Should be about 1200. If it is too low on the trailer, it won't have enough power to run with the load from water.

 

[Seadoocouple]

Its around 1200 I thought that was low because my 2006 is higher, the gas in the boat is a couple yrs old but seams ok

 

[Tim75]

Is it firing on all six?

 

[Seadoocouple]

It sounds like it is but I haven't ran a spark test on each cylinder

 

[jsgraham]

Had a similar problem last year; ended up being low fuel pressure. Make sure to test according to manual; key on, then monitor while running. Mine was good at startup, but dropped off to 20 lbs when running.

 

[Seadoocouple]

I turned the key so the pump would run the checked,the fuel at the little valve stem thing on top and it's just barley coming out. Is that where I test it? Also the fuel pump lools like a,square black thing but what is the big aluminum thing that the fuel goes into

 

[Tim75]

I turned the key so the pump would run the checked,the fuel at the little valve stem thing on top and it's just barley coming out. Is that where I test it? Also the fuel pump lools like a,square black thing but what is the big aluminum thing that the fuel goes into

There are 3 fuel pumps on this engine. The black cube has filter screwed into it. This is the lift pump that functions the same as a primer bulb on smaller outboards. The next pump is tucked in close to the block on port side. Driven by crankcase pressure/vacuum pulses. The last pump is "the big aluminum thing that the fuel goes into". That is the vst- injector pump. That pressure should be 36 psi, engine on or off at the tire valve. The tire valve is not supposed to release a huge amount of fuel. It is a test point.

When you run on the hose, how long will it run? If it only runs for a couple of minutes, you have a fuel problem. Check delivery from each pump. When is the last time your fuel filters were changed? 2 are easy. #3 is inside the vst. It is seldom the issue.

 

[Seadoocouple]

I don't think the small one has been changed ever and the one that looks like an oil filter looks pretty new. I just got the boat and it started on the trailer but never ran it more than 30 seconds but after I tried it in the lake is has not started. If I push the Schrader valve it sounds like air come like it's trying to purge but it's empty also I drained it and there wasn't much fuel in the vst. Should I hear the pump inside the vet or just the square one on the side, my number is 2602233168 if you want to text..thanks for,your help

 

[Seadoocouple]

The pump that come on with the key seams to have good volume so I pulled the line from the top of the vst and I can not blow into it so I'm pulling it apart. I figure there is a float or something like that in there stopping fuel from going in

 

[Seadoocouple]

What is the rpm on the trailer? Should be about 1200. If it is too low on the trailer, it won't have enough power to run with the load from water.

It's running around 1000 but its efi so idk if I can idle it up any

 

[Tim75]

It's running around 1000 but its efi so idk if I can idle it up any

Remove the brass screw at the bottom side of the vst tank. Arrange a catch pan. Key on. Should be a continuous stream of gas draining. If it's not continuous, it sounds like the float needle is stuck in its seat inside the vst. Common problem on engines that sit without running for long periods of time. Disassembly required.

Yes, the rpm can be raised. Refer to service book.